The present invention relates to a fluorescent lamp having a coating of thin film photocatalyst, which lamp is suitable for use in the home, a vehicle, and any space requiring lighting equipment for lighting the space or purifying air in the space, and wherein the cutting off of ultraviolet light radiated from the fluorescent lamp is desired.
Generally, in a closed space which is poorly ventilated, many malodorous substances, bacteria and fungi, or contaminating particulates are accumulated and spread in the air. The concentration of such undesirable substances in the air is in a range of the order of ppb-ppm or less, and the concentration of bacteria and fungi are much lower than that range. However, the undesirable substances, bacteria or fungi can negatively affect the human body, that is, malodorous substances produce uncomfortable feelings to a human being, and various kinds of bacteria and fungi can cause diseases, such as allergies and illnesses. Fat and oily organic substances can adhere to a surface of an object. This can cause the dust particles in the air to adsorb on the surface. Recently, there has been an urgent demand to develop cleaning techniques which are effective for deodorization, sterilization and decontamination of our living environment.
In the field of lighting equipment, techniques for decomposing malodorous substances by using the effects of a photocatalyst provided in lighting equipment have been proposed. For example, a lamp, on a surface of which a titanium oxide film is coated, is disclosed in JP-A-304237/1994 (corresponding to Germany Patent Application Laid-Open DE 4410476 A1).
In the above-mentioned laid-open documents, it is indicated that malodorous substances in air can be decomposed and removed by oxidation and reduction initiated by pairs of an electron and a hole generated in the titanium oxide film on which light is irradiated from the inside of the lamp.